Transfer of dye among salivary gland cells is not affected by genetic variations of the period clock gene in Drosophila melanogaster

Larval salivary gland cells of Drosophila melanogaster were injected with a fluorescent dye to assess strengths of intercellular communication among such cells, as influenced by mutations at the period locus and by a per transgene. This clock gene had been reported to increase the extent of dye transfer when mutated such that it shortens the period of biological rhythms; the previous study also showed that a per-null mutant decreased the strength of transfer among salivary gland cells. Our re-examination of this feature of larval physiology—in observer-blind analyses, using the per ^s and per ^o mutants as well as two per-normal strains—revealed no appreciable differences in extents of dye transfer among these four genotypes. These results are discussed in the context of emerging findings which suggest that the period gene's product controls pacemaker functioning as an intracellularly acting entity.